Max,
Whilst I agree that stop bars at clearance limits would be ideal, as Gonzo has said it would "drop" a bar for someone else giving them a green route through their clearance limit, OR by clearing the route to bring up the bar at say LOKKI the greens would go. In low vis we endeavour to keep stop bars lit at the delineation of GMC1,2 and 3 to prevent incursion into another GMC's ground space. This is fine when the movement rate is low as in LVP's but during normal conditions we have found that trying to keep the routes lit , expedites the traffic flow, reducing waiting times. At MOST points on the airfield we CAN bring up a bar at a clearance limit , such as short of Charlie or short of Link11 , but near the RHA's where space is tight and transfer of control goes from GMC to AIR it is almost impossible to bring up bars at Intermediate holding points like ETTIV or LOKKI, AND keep up the maximum departure rate off the runway. It would slow everything up too much.
Cheers A/T